How many people live in ?

Updated annually
In 2025, there were 12.7 million people living in Illinois. That makes Illinois the sixth-most populous state, home to 3.7% of people living in the US.

12.7M

population of Illinois (2025)

3.7%

Illinois share of the US population (2025)
The population of Illinois was about 2.6 times higher than it was in 1900. Between 2024 and 2025, the population of Illinois grew by about 16,100 people.

About 12.7 million people lived in Illinois in 2025. That's about 2.6 times more than in 1900.

Annual population estimates

What are Illinois's age demographics?

About 2.27 million Illinois residents were aged 65 and older in 2024. That represents 17.9% of the state’s population compared with 18% in the US overall.
Another 2.7 million Illinois residents, or 21.2% of the state’s population, were aged under 18. For comparison, children account for 21.6% of the US population.

A lower share of Illinois's population is is 65 and older than the US overall.

Population share by age group (2024)

What are Illinois's racial and ethnic demographics?

A state’s population may have racial and ethnic differences compared with the US overall. These figures reflect how people identified their race alone (not in combination with other races), and separate Hispanic or Latino ethnicity, following Census Bureau reporting standards.
Non-Hispanic white residents make up 58% of Illinois’s population, higher than the national share of 57.5%. Illinois also has a larger share of people identifying as non-Hispanic Black or African American (13.9%) than the US overall (12.6%).
In contrast, Illinois’s non-Hispanic two or more races population accounted for 1.9%, below the 2.5% share nationwide. The Hispanic population makes up 19.4% of the state, compared with 20% nationally.

A higher share of Illinois's population is is non-Hispanic Black or African American than the US overall.

Population share by race and ethnicity (2024)

What are Illinois's most populous counties?

In 2024, three out of 102 counties accounted for over half of Illinois's population:
  • Cook County, 5.18 million (40.8% of the population)
  • DuPage County, 937,100 (7.4%)
  • Lake County, 718,600 (5.7%)

In 2024, Cook County was the most populous county in Illinois.

Population estimates

What are Illinois's most populous cities?

The largest city in Illinois is Chicago with about 2.72 million residents in 2024.

Cities and counties in Illinois ranked by population

Cities and counties in Illinois ranked by population
1.

Chicago 

2,721,308
2.

Aurora 

180,710
3.

Naperville 

153,124
4.

Joliet 

151,837
5.

Rockford 

147,486
6.

Elgin 

114,701
7.

Springfield 

112,949
8.

Peoria 

111,696
9.

Champaign 

91,961
10.

Waukegan 

88,570

Keep exploring

Methodology

USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.

The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.

Page sources

USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.